Meibomian gland dysfunction (MGD) is one of the most common causes of an abnormality of the tear film lipid layer and evaporative dry eye. Numerous risk factors of MGD are reported. Its prevalence varies between countries from 20% to 60%, with the highest rate in Japan. MGD is a chronic, diffuse abnormality of the meibomian glands, commonly characterized by terminal duct obstruction and/or qualitative/ quantitative changes in the glandular secretion. This may result in alteration of the tear film, symptoms of eye irritation, clinically apparent inflammation and ocular surface disease.